The police on Friday had registered an FIR against the owner, captain and the crew members of the vessel.

"The carelessness of the captain, who is the in-charge of the ship, and the chief engineer, who should have taken care of technical aspects of vessel, has caused the ship to go down the water," said Bhoite.

The police did not comment when asked if more arrests were likely, but maintained they would continue to take appropriate actions as the probe progressed.

MV Rak, which was on its way from Indonesia's Tutung to Dahej in Gujarat with 60,000 tonnes of coal, had a 30-member crew of Indonesian, Jordanian and Romanian nationalities, who were rescued by the Indian Navy and Coast Guard personnel before it sank on Thursday.

Coast Guard sources said they could see oil layers at the place in the sea where the 225 metre-long vessel, which contained about 290 tonnes of fuel oil and 50 tonnes of diesel, sank but described the spill as "very negligible" and not capable of causing ecological problems.